Dave Plowman wrote:

I have touch dimmers that really are silent. Apart from the buzz, of
course.

I have a couple of ikea zigbee lamps, both are silent when on (even at
dimmest setting) but have a *just* audible SMPSU whine when they are
off, tempted to try potting one with resin, or giving it a 1/4W load to
shut it up.